President Donald Trump on Wednesday repeatedly denied telling the widow of slain Army Sergeant La David Johnson that her late husband "knew what he signed up for" when he joined the military. Sgt. Johnson was one of four U.S. Special Operations soldiers killed earlier this month in an ambush in the North African nation of Niger.

Rep. Frederica Wilson, D-Florida, first described hearing the president say this to Myeshia Johnson, Sgt. Johnson's widow, during a phone call on Tuesday which Wilson heard part of on speakerphone as they drove to the airport to meet Johnson's remains. The slain Army sergeant's mother, Cowanda Jones-Johnson, was also in the car and later confirmed Wilson's account of what happened.

Trump, however, denied over and over on Wednesday that he had ever said to Johnson's widow that the sergeant "knew what he signed up for." In a tweet, the president even claimed that he had "proof" that Wilson had "totally fabricated" her account of the call.

When reporters at the White House asked Trump what he said to Sgt. Johnson's widow in their phone call, Trump avoided the question. Instead, he crossed his arms and denied five times in rapid succession ever having told Johnson's widow that her late husband knew what he signed up for.

"I didn't say what that congresswoman said; didn't say it all. She knows it. And she now is not saying it. I did not say what she said, and I'd like her to make the statement again because I did not say what she said. Had a very nice conversation with the woman, with the wife, who was -- sounded like a lovely woman. Did not say what the congresswoman said, and most people aren't too surprised to hear that," Trump said.

"What was the proof, Mr. President?" a reporter asked, referring to Trump's tweet from Wednesday morning.

"Let her make her statement again and then you'll find out," Trump said cryptically, before repeating himself. "Let her make her statement again and then you'll find out."

Shortly after Trump's remarks, Wilson put out a tweet reaffirming her earlier account and chiding the president for not having used Ms. Johnson's name.

Trump's call to Johnson was one of four that the president made Tuesday to the families of U.S. Special Operations soldiers who were killed in Niger earlier this month.

Like presidents before him, Trump has made personal contact with some families of the fallen but not all. What's different is that Trump, alone among them, has picked a political fight over who's done better to honor the war dead and their families.

He placed himself at the top of the list, saying on Tuesday, "I think I've called every family of someone who's died" while past presidents didn't place such calls.

Trump initially claimed that only he among presidents made sure to call families. Obama may have done so on occasion, he said, but "other presidents did not call."

He equivocated Tuesday as the record made plain that his characterization was false. "I don't know," he said of past calls. But he said his own practice was to call all families of the war dead.

To read more from the Associated Press about previous presidents records of contacting so-called Gold Star families and Trump's own record on this, click here.